Story highlights

Russian official: Turkey's "highest political leadership ... are involved in this criminal business"

Turkish President: "No one has the right to slander Turkey, especially the slander of Turkey buying ISIS oil"

Turkish news: Syria bought oil from ISIS with help of a man with ties to Russian company

(CNN)Russian military officials laid out Wednesday what they say is "hard evidence" that Turkey is involved in an oil trade with ISIS, offering more detail on earlier claims that Turkish President Recep Tayyip Erdogan has flatly denied.

Officials presented photographs and videos that they said show links between Turkey and oil refineries in ISIS-controlled territory in Syria, estimating $3 million worth of oil per day was traversing this route before Russian airstrikes cut that roughly in half. Sergey Rudskoy, one of the military leaders, pointed to "three main routes (that) have been exposed for the transportation of oil to Turkey" -- one ending in Turkish ports on the Mediterranean Sea, another at an oil refinery in Batman and a third in Cizre.

Antonov said"the highest political leadership of the country -- President Erdogan and his family -- are involved in this criminal business," crediting Russian journalists for their reports tyingone of Erdogan's sons to a role in the scheme.

"If they think the evidence is fake, let them make these areas available to journalists," Antonov said, placing the burden on the Turks to disprove Russia's claims.

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Keeping up his own tough talk, the Turkish President blasted the allegations as wrong Wednesday during a speech at Qatar University.

"No one has the right to slander Turkey, especially the slander of Turkey buying ISIS oil," Erdogan said. "Turkey has not lost its moral values to buy oil from a terror organization."

War of words

Wednesday's remarks from both sides were the latest verbal salvos since Turkey shot down a Russian warplane on November 24. Ankara says the plane was given ample warning and was in Turkish airspace; Moscow denies both assertions, saying the aircraft was downed over Syria. One of its pilots was killed, while another was rescued.

"He also benefits from the regime through favorable treatment including the award of a contract (as a subcontractor) with Stroytransgaz, a major Russian oil company," the document said.

Assad: Erdogan 'lost his nerve'

Assad and others in his government insist they want to destroy ISIS, not support it monetarily. Their goal is to win the ugly, complicated, years-long civil war, which U.N. humanitarian chief Stephen O'Brien estimated this summer has killed more than 250,000 people, displaced some 7.6 million within Syria and spurred over 4 million to escape to other countries.

Photos:Syria's civil war, in pictures

Displaced Syrian residents wait to receive food aid distributed by the UN Relief and Works Agency at the besieged al-Yarmouk camp, south of Damascus, Syria, on January 31, 2014. According to the UN Envoy for Syria, an estimated 400,000 Syrians have been killed since an uprising in March 2011 spiraled into civil war. See how the conflict has unfolded.

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An injured man lying in the back of a vehicle is rushed to a hospital in Daraa, Syria, on March 23, 2011. Violence flared in Daraa after a group of teens and children were arrested for writing political graffiti. Dozens of people were killed when security forces cracked down on demonstrations.

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Anti-government protesters demonstrate in Daraa on March 23, 2011. In response to continuing protests, the Syrian government announced several plans to appease citizens.

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Syrian children walk over bricks stored for road repairs during a spontaneous protest June 15, 2011, at a refugee camp near the Syrian border in Yayladagi, Turkey.

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Jamal al-Wadi speaks in Istanbul on September 15, 2011, after an alignment of Syrian opposition leaders announced the creation of a Syrian National Council -- their bid to present a united front against Bashar al-Assad's regime and establish a democratic system.

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Delegates from Arab League member states and Turkey discuss a response to the government's crackdown in Syria on November 16, 2011.

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Supporters of al-Assad celebrate during a referendum vote in Damascus on February 26, 2012. Opposition activists reported at least 55 deaths across the country as Syrians headed to the polls. Analysts and protesters widely described the constitutional referendum as a farce. "Essentially, what (al-Assad's) done here is put a piece of paper that he controls to a vote that he controls so that he can try and maintain control," a US State Department spokeswoman said.

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Syrian refugees walk across a field in Syria before crossing into Turkey on March 14, 2012.

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Rebel fighters with the Free Syrian Army capture a police officer in Aleppo, Syria, who they believed to be pro-regime militiaman on July 31, 2012. Dozens of officers were reportedly killed as rebels seized police stations in the city.

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A Free Syrian Army fighter runs for cover as a Syrian Army tank shell hits a building across the street during clashes in the Salaheddine neighborhood of central Aleppo on August 17, 2012.

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Family members mourn the deaths of their relatives in front of a field hospital in Aleppo on August 21, 2012.

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A Syrian man carrying grocery bags dodges sniper fire in Aleppo as he runs through an alley near a checkpoint manned by the Free Syrian Army on September 14, 2012.

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Free Syrian Army fighters are reflected in a mirror they use to see a Syrian Army post only 50 meters away in Aleppo on September 16, 2012.

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Smoke rises over the streets after a mortar bomb from Syria landed in the Turkish border village of Akcakale on October 3, 2012. Five people were killed. In response, Turkey fired on Syrian targets and its parliament authorized a resolution giving the government permission to deploy soldiers to foreign countries.

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A Syrian rebel walks inside a burnt section of the Umayyad Mosque in Aleppo hours before the Syrian army retook control of the complex on October 14, 2012.

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An Israeli tank crew sits on the Golan Heights overlooking the Syrian village of Breqa on November 6, 2012. Israel fired warning shots toward Syria after a mortar shell hit an Israeli military post. It was the first time Israel fired on Syria across the Golan Heights since the 1973 Yom Kippur War.

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Smoke rises in the Hanano and Bustan al-Basha districts in Aleppo as fighting continues through the night on December 1, 2012.

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The bodies of three children are laid out for identification by family members at a makeshift hospital in Aleppo on December 2, 2012. The children were allegedly killed in a mortar shell attack that landed close to a bakery in the city.

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A father reacts after the deaths of two of his children in Aleppo on January 3, 2013.

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Syrians look for survivors amid the rubble of a building targeted by a missile in the al-Mashhad neighborhood of Aleppo on January 7, 2013.

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Rebels launch a missile near the Abu Baker brigade in Al-Bab, Syria, on January 16, 2013.

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An aerial view shows the Zaatari refugee camp near the Jordanian city of Mafraq on July 18, 2013.

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The UN Security Council passes a resolution September 27, 2013, requiring Syria to eliminate its arsenal of chemical weapons. Al-Assad said he would abide by the resolution.

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Residents run from a fire at a gasoline and oil shop in Aleppo's Bustan Al-Qasr neighborhood on October 20, 2013. Witnesses said the fire was caused by a bullet from a pro-government sniper.

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Syrian children wait as doctors perform medical checkups at a refugee center in Sofia, Bulgaria, on October 26, 2013.

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An injured man is helped following an airstrike in Aleppo's Maadi neighborhood on December 17, 2013.

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A man holds a baby who was rescued from rubble after an airstrike in Aleppo on February 14, 2014.

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A US ship staff member wears personal protective equipment at a naval airbase in Rota, Spain, on April 10, 2014. A former container vessel was fitted out with at least $10 million of gear to let it take on about 560 metric tons of Syria's most dangerous chemical agents and sail them out to sea, officials said.

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A Free Syrian Army fighter fires a rocket-propelled grenade during heavy clashes in Aleppo on April 27, 2014.

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A giant poster of al-Assad is seen in Damascus on May 31, 2014, ahead of the country's presidential elections. He received 88.7% of the vote in the country's first election after the civil war broke out.

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Rebel fighters execute two men on July 25, 2014, in Binnish, Syria. The men were reportedly charged by an Islamic religious court with detonating several car bombs.

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Photographs of victims of the Assad regime are displayed as a Syrian army defector known as "Caesar," center, appears in disguise to speak before the House Foreign Affairs Committee in Washington. The July 31, 2014, briefing was called "Assad's Killing Machine Exposed: Implications for U.S. Policy." Caesar, apparently a witness to the regime's brutality, smuggled more than 50,000 photographs depicting the torture and execution of more than 10,000 dissidents. CNN cannot independently confirm the authenticity of the photos, documents and testimony referenced in the report.

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Volunteers remove a dead body from under debris after shelling in Aleppo on August 29, 2014. According to the Syrian Civil Defense, barrel bombs are now the greatest killer of civilians in many parts of Syria. The White Helmets are a humanitarian organization that tries to save lives and offer relief.

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Medics tend to a man's injuries at a field hospital in Douma after airstrikes on September 20, 2014.

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A long-exposure photograph shows a rocket being launched in Aleppo on October 5, 2014.

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Rebel fighters dig caves in the mountains for bomb shelters in the northern countryside of Hama on March 9, 2015.

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Nusra Front fighters inspect a helicopter belonging to pro-government forces after it crashed in the rebel-held Idlib countryside on March 22, 2015.

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A Syrian child fleeing the war gets lifted over fences to enter Turkish territory illegally near a border crossing at Akcakale, Turkey, on June 14, 2015.

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A refugee carries mattresses as he re-enters Syria from Turkey on June 22, 2015, after Kurdish People's Protection Units regained control of the area around Tal Abyad, Syria, from ISIS.

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A sandstorm blows over damaged buildings in the rebel-held area of Douma, east of Damascus, on September 7, 2015.

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Members of a Syrian opposition group attack the headquarters of al-Assad regime forces in the Aleppo villages of Nubul and al-Zahraa on February 12, 2016.

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This still image, taken from a video posted by the Aleppo Media Center, shows a young boy in an ambulance after an airstrike in Aleppo, Syria, on August 17, 2016. It took nearly an hour to dig the boy, identified as Omran Daqneesh, out from the rubble, an activist told CNN. The airstrike destroyed his home, where he lived with his parents and two siblings. Director of the Aleppo Media Center Yousef Saddiq said Omran's 10-year-old brother, Ali, died from his injuries.

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Smoke rises after an airstrike in Aleppo on October 4, 2016.

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Arabic writing that reads "some day we will return" is seen on a bus window as civilians evacuate Aleppo on December 15, 2016. The evacuations began under a new ceasefire between rebels and pro-government forces.

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This photo, provided by the activist Idlib Media Center, shows dead children after a suspected chemical attack in the rebel-held city of Khan Sheikhoun on April 4, 2017. Dozens of people were killed, according to multiple activist groups. The United States responded a few days later by launching between 50-60 Tomahawk missiles at a Syrian government airbase. US officials said the base was home to warplanes that carried out the chemical attack. Syria has repeatedly denied it had anything to do with the attack.

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Members of the UN Security Council raise their hands on April 12, 2017, as they vote in favor of a draft resolution that condemned the reported use of chemical weapons in Syria.

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Residents of the war-torn city of Douma break their Ramadan fast on June 18, 2017.

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A member of the Syrian pro-regime forces fires a machine gun as a comrade holds his feeding ammunition belt on November 11, 2017. It was during an advance toward rebel-held positions west of Aleppo.

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A child receives medical treatment after a village was attacked in the rebel-held Eastern Ghouta region on February 25, 2018. Several people were treated for exposure to chlorine gas, opposition groups said, as airstrikes and artillery fire from the regime continued. CNN was unable to independently verify claims that chlorine was used as a weapon.

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Bodies lie on the ground in the rebel-held city of Douma, Syria, on April 8, 2018. According to activist groups, helicopters dropped barrel bombs filled with toxic gas on Douma, which has been the focus of a renewed government offensive that launched in mid-February. The Syrian government and its key ally, Russia, vehemently denied involvement and accused rebel groups of fabricating the attack to hinder the army's advances and provoke international military intervention.

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Damascus skies erupt with anti-aircraft fire as the US and its allies launch an attack on Syria's capital early on April 14, 2018. US President Donald Trump announced airstrikes in retaliation for Syria's alleged use of chemical weapons. Trump says the strikes are part of a sustained military response, in coordination with France and the United Kingdom.

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In a rare interview Sunday, Assad stood behind one of his few allies in this crisis, Putin. The Syrian President said the warplane shoot-down "has shown the real intention of Erdogan, who, let's say, lost his nerve just because the Russian intervention has changed the balance on the ground."

"So the failure of Erdogan in Syria, the failure of his terrorist groups, means his political demise. So he wants to do anything in order to put obstacles in front of any success," he told a reporter for Czech Television.

The Syrian government has lauded Russian airstrikes for making major inroads against "terrorists." But some in the West questioned if Moscow has exclusively gone after ISIS or has lashed out at others opposing Assad's government, including more moderate factions opposing him.

Erdogan has been among these voices, claiming that ISIS fighters weren't in the part of northern Syria being bombed by Russia when its warplane was shot down but rather that "our brothers and sisters, Turkmen" were there.

Russia's alleged violation of Turkish airspace has been a point of friction in the past.

U.S. Secretary of State John Kerry said Wednesday that Turkey will seal off the unsecured part of its border with Syria.

He said there is still a 98-kilometer (61-mile) stretch of the border that is not sealed.

The closure is aimed at stopping the movement of illegal oil as well as the flow of foreign fighters from Syria to Turkey.

Kerry also reiterated his country's opposition to Assad remaining in power, while expressing hope that the structure of Syrian government can remain. He said that Washington and its allies want to avoid a collapse of authority like what happened in Iraq after the ouster of Saddam Hussein.

"Our hope and prayer is that indeed Russia and Iran will stay committed to the concept of a transition that really legitimizes governance in Syria in a way that can bring about a ceasefire and in a way that can bring an end to the conflict," Kerry said. "That is not regime change, that is Assad change."